Is impossible negative still a viable option-Precision

8+ 4441 hands responding to strong 1♣ cause problems if 1M responses promises a 5+ card suit.
Using the impossible negative 1♣-1♦ in addition to hands with 0-7 hcp includes all 4441 with 8+ hcp later jumping in singleton or sometimes NT to show strong hand. Having the negative bid include strong hands caused problems. The normal solution is to use jump responses to show 4441 hands which account for about 2% of possible GF responses.
I have seen people use 1 bid to handle all 4441 handle. Have also seen fairly often people using 2 or 4 bids to show the 4441 hands.
Have even seen people use 8 bids, but they were using 4-bids whose use is pretty rare anyways so no loss.

Bidding has improved since the 1970's when the impossible negative was used.
In normal bidding it is not uncommon to have 2 ranges for splinter's.
Applying this method to impossible negatives you can use 1 bid to show an unnamed splinter with 6-7 hcp and jumps to show an impossible negative.
One knock against the impossible negative was it was hard to differentiate between a maximum negative and an impossible negative.
Here is scheme after 1♣-1♦-1♥
2♠ - 11+ hcp & 3+ controls 1-4-4-4 strong impossible negative four hearts and a singleton spade GF2NT: 8+ hcp 4-1-4-4 impossible negative with singleton heart 3♣: 11+ hcp & 3+ controls 4-4-4-1 strong impossible negative four hearts and a singleton club.3♦: 11+ hcp & 3+ controls 4-4-1-4 strong impossible negative fourhearts and a singleton diamond.3♠: 5-7 hcp four+ hearts and an unnamed singleton or void. ………..3NT: relay for shortness, 4H=short spades3NT: 8-10 hcp or 11+ hcp <3 controls 1-4-4-4 impossible negative four hearts and a singleton inspades.4♣: 8-10 hcp or 11+ hcp <3 controls 4-4-4-1impossible negative fourhearts and a singleton in clubs.4♦: 8-10 hcp or 11+ hcp <3 controls 4-4-1-4 impossible negative four hearts and a singleton in diamonds.

The bigger problem is after interference if the bidding has gone 1♣-(P)-1♦Interference is likely to occur in responders singleton possibly with a raise by overcaller's partner. So, bidding may get high.If not too high responder can make a normal cue-bid with 5-7 or 6-7 hcp and 0-2 cards in suit shown. With an impossible negative 8+ hcp and singleton in shown suit responder can do a jump cue-bid to show 4441.

If interference is not in responder's singleton it is more difficult to distinguish between 6-7 maximum negative and 8+ impossible negative.Double showing values is the likely bid one must make.But remember opener has a chance to bid. If opener bids a suit responder has a fit with, responder may be able to show fit in a forceful manner (likely a non-jump cue-bid with a follow-up bid).If opener bids responder's singleton responder can bid some number of NT or make a penalty double to show an impossible negative.

So, my point is that there is an alternative to using 4 bids for a rare possibility.

I'm not a fan. Having positive responses in 1♦ is just asking for trouble - although if it were legal in ACBL-land I could convert to Moscito style where all the POSITIVE hands go into 1♦ and 1♥ is the bad bid.

These days I'm playing SMP, which is basically Meck-lite.

All 8+ hands go through either 1♥ (Nebulous 8-11), with various followups, or in this case a direct 1♣-2♠ is a 4441 12+

Pretty easy to learn as relays are kept to a minimum and most auctions develop naturally. The 1♥ over 1♣ is a big win for keep things low on simple hands, and overall the system just works well. 1♦ is 2+ and 2♣ is 6+.

It's just a good pragmatic system that works well in the current meta. (e.g. frequent overcalls) and keeps mad science to a minimum.

I'm not a fan. Having positive responses in 1♦ is just asking for trouble - although if it were legal in ACBL-land I could convert to Moscito style where all the POSITIVE hands go into 1♦ and 1♥ is the bad bid.

These days I'm playing SMP, which is basically Meck-lite.

All 8+ hands go through either 1♥ (Nebulous 8-11), with various followups, or in this case a direct 1♣-2♠ is a 4441 12+

Pretty easy to learn as relays are kept to a minimum and most auctions develop naturally. The 1♥ over 1♣ is a big win for keep things low on simple hands, and overall the system just works well. 1♦ is 2+ and 2♣ is 6+.

It's just a good pragmatic system that works well in the current meta. (e.g. frequent overcalls) and keeps mad science to a minimum.

Concur with the above -- unless playing something like IMPrecision (which uses 1♦ for the really strong positive hands) -- it's much better to not have any positive responses in 1♦. BTW, my preferred version of SMP is the Grue-Moss version which uses 1♥ for the 12+ hands, with 8-11 showing suits directly. IMO, it's better than the other way around, albeit at the cost of slightly increased memory load. Their version also allows symmetric relays (at +1 or so), should the need arise, while keeping the option of bidding naturally with unbalanced hands.

Currently, I'm seeing systems that don't use the impossible negative. Instead, they replace all the immediate 3 level bids to fill that void. For instance, one treatment I've seen is: 3c = 8-11, black singleton 4441; 3d = 8-11, red singleton 4441; 3h = 12+, 4-1-4-4; 3s = 12+, 1-4-4-4; 4c = 12+, 4-4-4-1; 4d = 12+, 4-4-1-4. This differentiates hands that just want to force to game, and hands with real slam potential. The 6-7 point 4441 hands you can start with 1d, then bid aggressively from there. For the 3c/3d bid, opener can make a step bid as a relay to find the singleton.

In several Strong Club partnerships we put all the responder's G.F. 4441 hands into the initial response of 2S. Now 2NT by opener asks for the singleton.
Alternately, one can use 2H and now 2S asks for 1-under the singleton. This allows opener several options to investigate slam.
1) Bidding the singleton can be Beta for controls and a suit bid other than the singleton can be RKC, or
2) Bidding the singleton is a slam try showing little honor wastage opposite the singleton asking for cue Bidding.